Lens grinding and the like machine



Nov. 2, 1954 v G. HAGSTROM LENS GRINDING AND THE LIKE MACHINE 4Sheets-Sheet 1 Filed Sept. 29, 1950 Nov. 2, 1954 a. HAGSTROM 2,693,053

LENS GRINDING AND THE LIKE MACHINE Filed Sept. 29. 1950 4 Shee ts-Sheet2 r I. inventor:

Nov. 2, 1954 G. HAGSTROM LENS GRINDING AND THE LIKE MACHINE 4Sheets-Sheet 3 Filed Spt' 29, 1950 ATTORNEY Nov. 2, 1954 G. HAGSTROM2,693,058

I LENS GRINDING AND THE LIKE MACHINE Filed Sept. 29, 1950 4 Sheets-Sheet4 beveled around the lens.

United States Patent O LENS GRINDING AND THE LIKE MACHINE GotthardHagstrom, Greenwich, Conn.

Application September 29,1950, Serial N 0. 187,595

25 Claims. (Cl. 51-101 This invention relates to certain improvements inoptical lens grinding and the like machines; and the nature and objectsof the invention will be readily apparent to and understood by thoseskilled in the art IrOrn the following explanation and detaileddescription of the accompanying drawings illustrating what I at presentconsider to be a .preferred embodiment or mechanical expression of agrinding machine of the invention for grinding optical lenses, fromamong various other embodiments, designs, adaptations, combinations andcon structions and uses, of which the invention is capable within thebroad spirit and scope thereof as defined by the appended claims.

Optical lenses after being surface ground to the required prescription,must thereafter usually be first edge ground to provide a flatperipheral edge surface therearound, if of the so-called -rimless typeof lens, while, if

of the type to be mounted in a frame, the lens must after such edgegrinding then have the ground edge thereof In accordance with thegenerally prevailing practices and techniques, such edge grinding andedge beveling are performed as two (2) separate and distinct operationson two (2) separate and distinct grinding machines. Thus, with theprevailing practices, it is necessary to mount and edge grind a lens inan edge grinding machine, then remove the lens and bevel by handoperation, or mount in bevel edging machine which reduces the lens tosize and bevels in the limited grinding area of a V-notched grindingwheel.

One of the general objects of my present invention, with particularreference to adaptations of the invention -to machines for optical lensgrinding, is to provide a single machine capable of etficientlyprecision grinding both the edge grind and the bevel grind around a lenswithout the necessity of removing the lens and resetting it, and

by mere simple adjustments of the machine to convert it for either edgegrinding or bevel grinding.

Optical lenses vary according to' type and to the prescription to whichthey are shaped and surface ground. Such lenses frequently have theirperipheral or surrounding edgeportion of wave or sinuous form around themajor physical axis of the lens, that is to say, the peripheraledgeportion of the lens does not lie at all portions thereof andtherearound in a plane perpendicular or normal to the axis about whichthe lens will be rotated in grindinga bevel thereon. Machines of the artfor grinding a bevel on and around the ground edge of a lens haveresorted to various mechanical-expedients for meeting the conditionspresented by such peripheral edge shapes and forms of lenses, includingprovidingfor relative movements axially between the lens'and the cir--cular grinding wheel and controlling such relative movements positivelybytemplates, patterns, cams, or the like -mechanical components andorganizations. Usually edge beveling is carried out by a circulargrinding wheel having a V-groove in and around its peripheral edge intowhich the peripheral edge portion of the lens engages, under the depthor radial movement control of a template for the particular lens beingground. 1 hemachines in general usefor lens edge beveling are ofnecessity of vrelatively complicated character, particularlyinthetemplate, pattern or other controls required to meet the foregoingconditions.

A further general object of my invention is to eliminate certain of thestructural and mechanical complexities of the lens beveling, grindingmachines of the art byprovidinga design, arrangement and mounting ofa,circulargrinding .wheelby which the necessitywfor mechanism forpositive control of the relative axial movements between the grindingwheel and the lens may be eliminated, while obtaining increasedefliciency and precision for the bevelegrinding operation.

A further object is to provide a design and mounting of a circulargrinding wheel having a peripheral bevel grinding groove therearoundbywhich the grinding wheel is ,caused to float in a balanced conditionduring rotation thereof yet which may be oscillated from and across itsbalanced position by relatively light pressures applied thereto in theproper directions, so that, the lens itself when in grinding contact inthebevel grinding groove of the grinding wheel functions as the patternor template which effects the required positive directional moveandefficient mechanism for effecting such oscillation.

Another object is to provide such oscillating mechanism which will becapable of selecting adjustments by an iop'erator between active andinactive positions relative to the grinding wheel, without interferingwith the floating mountingofthat wheel orits functioning when theoscillating mechanism is in inactive position.

A further object is to provide for positive oscillation of the grindingwheel for grinding surface dressing, through a greater predetermineddegree of oscillation than that through which the grinding wheel isoscillated for edge grinding.

And a further object is to provide for'elfecting such dressingoscillation of the grinding wheel through the medium of the .samemechanism by which edge grinding oscillation is carried out; and furtherto provide for selective'setting'by-the operator of the oscillatingmechanism for either-edge beveling or grinding surface dressing,respectively.

With the foregoinggeneral objectsand certain other objects, features andresults in view which will be apparent from-the following detaileddescription, my inventron consists in certain novel features in designand construction, and in combinations and sub-combinations of parts andelements, all'as will be more specifically referred to and specified'hereinafter.

Referring to the accompanying drawings, in which similar referencecharacters refer tocorresponding parts and elements throughout theseveral figures thereof:

Fig -l is an exploded view showing certain of the essential componentsmaking up the grinding wheel and its mounting and the drives for thegrinding wheel and for the lens and its-template, the part s being shownmore or less schematically.inperspective'in the relativepositionsthereofto be assumed in assembly.

Fig. 2 is a view inside elevationof the grinding wheel with a lens ingrinding engagement therewith, taken from that side of the-wheel withwhichthe wheel controlling .pms are associated, such pins being shown intransverse vertical section.

.Fig. 3 is a viewiin vertical section through the grinding wheel and itsmounting, a lens being shown in edge elevation ingrindingengagement inthe beveling groove of the wheel.

;Fig. 4 is aview .in :edge elevation of the grinding -wheel, showingitsmounting and controllingpins in side elevation.

Fig. 5 is a view-invertical longitudinal section through aform oflensgrmdmgmachine of the invention, in-

cluding the componentsillustratedinFigs. l to 4.

Fig. .6 is a vertical transverse section through the machine. of Fig. 5,taken-as on the line 6-6 of'Fig. 5.

Fig. 7 is a'vertical transverse sectional view taken as on the lines 77of Fig. 5.

A design and arrangementv of an optical grinding machine embodyingtheprinciples and features of mvinven- .tromand capableof.efiicientjfunctioning for. either lens edge grinding or lens edgebeveling, is disclosed in the accompanying drawings by way of anexample. It is to be understood that certain of the principles andfeatures of the invention, as exemplified in the optical lens grindingmachine illustrated and described herein, are not limited to solelymachines for optical lens grinding, but are of general utility asadaptations to various types of surface or power grinding machinesirrespective of the particular work or uses for which such machines maybe intended or adapted.

Referring now to Fig. 1 of the drawings, there is shown therein more orless schematically the essential components and organizations making upthe optical lens grinding machine of the example machine of Fig. 5. Oneof the basic components of the machine is the grinding wheel drivingshaft 10 which is mounted in horizontally disposed position in suitablebearings in supporting structure carried on the machine frame structure79. This shaft 10 is driven from a motor M, or other suitable source ofdriving power, through the medium of a pulley and belt drive comprisedby the motor driving pulley 11 and driven pulley 12 mounted on one endof the grinding Wheel driving shaft 10, with a belt 14 in operativedriving connection between the pulleys. Obviously any other suitabletype of drive or power transmission may be utilized if desired. In theexample machine it may be considered that the pulley 12 and the grindingwheel drive shaft 10 are driven from motor M through pulley 11 and belt14, at a rate of 900 R. P. M., but such rate of rotation is given hereinpurely by way of example and not of limitation.

In accordance with the basic and one of the important features of myinvention, a circular grinding wheel designated in its entirety as aunit by the reference character G, is mounted on driving shaft 10 forrotation by and about the axis of that shaft, but in such manner thatthe grinding wheel can be made to float for limited oscillation on andrelative to the shaft 10 about an axis perpendicular to the axis of thedriven shaft, by very light forces applied to the periphery of the wheelin directions acting axially relative to the wheel and its drivingshaft.

Referring to Figs. and 6, the lens grinding machine in the instantexample includes a generally rectangular, vertically disposed, box-likeframe structure 70 Within which there is mounted and supported inelevated position a wall or base 71 disposed horizontally thereacrossand therewithin and providing the upwardly extending pedestal or columnstructure '72, in and across which the grinding wheel driving shaft ismounted and journaled in the spaced bearings 10a. Pulley 12 is mountedon one end of shaft 10 at the outer side of column structure 72, whilethe shaft 10 at its opposite or inner end projects a distance inwardlyacross the column structure 72 in position to mount on its inner end forrotation therewith the grinding wheel unit G- In carrying out andexpressing mechanically in the example machine, that feature of myinvention by which the grinding wheel G is made to float in a laterallybalanced condition, I have mounted on the inner end of the wheel drivingshaft 10, a ball or generally spherically formed member 20. The grindingwheel G is mounted on ball member 20 in direct driven connectiontherewith for rotation about the aligned axes of the shaft and wheelwith the wheel being held against rotation on and relative to the ballmember 20 and shaft 10. However, provision is made for rocking oroscillation bodily of the wheel G about an axis intersecting butperpendicular to the axis of rotation, so that the wheel may thus berocked on and independently of the ball member 20 and its shaft 10 indirections axially of the shaft.

in this instance, the grinding wheel unit G includes a hub 39 having amain wheel body or flange in the form of a circular plate 31 extendingradially therefrom and therearound. The wheel body or plate 31terminates on and around its peripheral edge in a circular shoulderedseat 32 on and around which the annular grinding stone component 33 ofthe wheel is mounted in suitably attached and locked position thereon.Grinding wheel hub 30 is formed with an axial bore therethrough which ispartially closed at one end of the hub by an annular, frustro-conicalend wall 34. End wall 34 is precision ground or otherwise formed aroundits inner surface within the hub bore to provide a complementary, curvedspherical surface 34a which forms a sliding fit with and around theouter end portion or side of ball member 20, as will be clear byreference to Figs. 3 and 5. A suitable retaining and bearing ring 35 isthreaded into the inner, wide diameter end of the hub bore around andreceiving therethrough the shaft It). The inner side of this retainingand bearing ring 35 is formed curved to provide a complementary surface35a for receiving and fitting against the inner side of ball member 20with a sliding fit. Thus, in the absence of restraint other than theinternal width of the driving shaft receiving bore 35b of ring member35, the grinding wheel G would have universal mounting on and berotatable and rockable gnivesally about a center provided by the ballmem- However, in accordance with my invention a positive drivingconnection is provided between ball member 20 and the hub .30 ofgrinding wheel unit G, which fixes the ball member and the grindingwheel against rotation relative to each other about the axis of shaft10, while permitting limited rocking or oscillation of the grindingwheel unit on the ball in directions axially of the shaft and laterallyrelative to the wheel. In the present example, such driving connectiontakes the form of a pin 36 extending radially inwardly from the hub 30of wheel 6 into the bore thereof, with'this pin slidably received in acircumferentially disposed slot or groove 21 (see Fig. l) which isdisposed axially of shaft 10 with the longitudinal center thereof lyingin a plane passing through the axis of the shaft and the center of ballmember 29. Thus mounted and connected, the grinding wheel G is placed inpositive driven connection with the spindle it) for rotation therewithas a unit about the axis of the spindle and the center of ball member 20with the grinding wheel G free to be rocked or oscillated through alimited range in a direction axially of spindle 10 and about the centerof ball member 20. Hence, the grinding wheel G while being maintained inpositive driven connection with the shaft 10 by the pin and grooveconnection 36-21, may be rocked or oscillated laterally in directionsaxially of the shaft. During such oscillatory movements driving pin 36,which has an outside diameter to form a running fit in groove 21, mayrock in and through the groove of the ball member without play laterallyor radially of the pin in the groove.

Upon rotation of grinding wheel G by the shaft 10, if the wheel islaterally unconstrained, the wheel will, due to the action ofcentrifugal forces and the resulting gyroscopic effect, assume andmaintain its normal position of rotation in a plane perpendicular to theaxis of shaft 10 and wheel rotation. I have discovered, and I havedevised the example embodiment as an operative mechanical expression ofsuch discovery, that if the grinding wheel G is displaced or rockedlaterally on the ball member 2t about the center of the ball to aposition deflected from its normal position of rotation in a planeperpendicular to the axis of the shaft 10, and is then held ormaintained in such deflected position by forces which balance the forcesacting to restore the wheel to its normal position, there will result ineffect a balanced condition of the wheel in which the wheel floats aboutthe center of the ball member. In such a deflected position of balanceor floating which is attained during rotation of the grinding wheel G,the wheel may be caused to oscillate about the center of the ball member20 by very light, laterally acting deflective forces applied to thewheel in either direction axially of shaft 1d. The angularly displacedor deflected floating position of grinding wheel G may be taken to be inthe example hereof, as of the order of three degrees (3") of deflection.Such position of angular displacement or deflection of grinding wheel Gabout ball member 20, is illustrated in Fig. 4.

Referring now to Figs. 5 and 6, the angular displacement or deflectionof grinding wheel G may be effected by'a pair of deflecting pins 40 and41 which are mounted in horizontally disposed position extending throughand for reciprocation in a vertically disposed supporting bracketstructure 73 mounted on the base 71 within frame 76 at and spaced fromthe outer side of the grinding wheel G. The pins 40 and 41 are mountedin bracket structure 73 in positions engaging at their inner ends theadjacent side of the plate or body 31 of the grinding wheel G. As willbe clear by reference to Figs. 2 and 6, these pins 40 and 41 are sopositioned as garnets to engage the wheel body 31 at diametricallyopposite locations thereon, with pin 40 located below and pin &1 locatedan equal distance above a horizontal plane passing through the axis ofrotation of wheel G. In order that the side of wheel body 31 may haveminimum friction, rotative engagement with the inner ends of thedeflecting pins '40 and '41, I have provided an annular, thrust type ofbearing assembly 42 on wheel body 31 around hub 30, with the outerannular ring or race plate '43 of this unit engaged by the inner ends ofpins 40 and 41. Thus, the grinding wheel G may be rotated while engagedby pins '40 and 41 for wheel defiection, with a minimum of friction,even with the pins exerting the forces necessary to laterally displaceor deflectthe grinding wheel to the desired angular position. Thegrinding wheel deflecting pins 40 and 41 are mounted and adjusted in thebracket structure 73 so as to angularly displace and hold the grindingwheel continuously in its displaced position against the forcesgenerated by rotation of the grinding wheel which act to restore thewheel to its normal position of rotation about the center of ball member20. These pins can be fixed or set in the necessary positions and, ifdesired or found expedient, thepins may be provided with suitable shockand vibration absorbing springs 40a and 41a. These springs may be of thecompression type requiring forces to compress them of a greatermagnitude than the forces normally acting to restore grinding wheel Gfrom the angularly deflected position to its normal position ofrotation.

, The annular grinding component or ring 33 (see Fig. 1) of grindingwheel G may be formed of any suitable one of the well known grindingwheel materials for lens grinding, such as a diamond impregnatedmaterial. The outer periphery of grinding component 33 is formedcircular and truly concentric with the ball member of the wheelmounting, and is curved transversely to provide the transversely convexperipheral edge grinding surface 33a therearound for performing lensedge grinding operations. In addition the grinding component 33 isprovided with a groove 33b in and around the perip'eral grinding surface3311, with this groove being truly concentric with the ball member 20.Groove 33b "is provided for performing the lens edge bevelingoperations, and in this example, is located on and around grindingcomponent 33 with the groove being of V-sh'ape 'in, cross section andhaving its apex lying in theplane of the plate-like body 31 of thewheel, as will be clear by reference to Fig. 3 in particular.

A lens L to be either edge ground or bevel ground, is mountedandpositioned in a suitable work holding and rotating mechanism, with thelens held thereby in position'generally parallel with the grinding wheelG to engage the edge of the lens in operative grinding relation with'either the grinding surface 33 1 or the edge beveling groove 33b of thegrinding wheel. Referring to Fig. 5 in particular, a lens L to be groundis releasably clamped and secured in operative position between therotati've clamping "jaws or members '51 and '52 of the work holdingmechanism, in a manner generally familiar in this art. The work holdingmechanism which includes'the clamping jaw members 51 and 52, is mountedon a head or cover structure 80 which is 'pi'votally mounted or hingedin position on and across the upper end of the machine frame structure70 for swinging forwardly'and downwardly to operative grinding positionwith the lens L in grinding engagement with grinding wheel G, and forswinging upwardly and "rearwardly from operative position to avertically dis posed, inactive position with a lens completely removedfrom grinding wheel G, as clearly shown in Figs. 5 and 6. i Clampingjaws 51 and 52 are mounted in heador cover "80 in axial alignment andpositioned disposed with their axes generally parallel with the axis ofrotation of grinding wheel driving shaft 10. The clamping jaws 51 and.52 are generally centrally located in the cover structure "80 in a wellor recess formed by a reen'trant portion 80a of the cover structure. Inthis example, clamping ja'wSjl is mounted on the inner end of a driven,rotary shaft 53 which is journaled in suitable bearings '53a provided bythe cover structure. One of the bearmgs 5321 is provided in a sidewallof cover structure '80 v'vith"shaiitSS extended outwardly beyond suchside wall and mounting'at the outerend thereof the usual templet "6 T.The jaw 51 and temple't T are rotated by and with shaft 53, with theternplet T providing by its peripheral edge contour a precise replica orpattern'of the finished, ground contour which it is desired 'to grind onthe lens L. A suitable anvil (not shown) is positioned for engagement bythe peripheral edge of templet T "in the general manner familiar tothose skilled "in this art. In operative position of "cover structurewith the periphery of the lens L in engagement with grinding wheel G,the templet T rotatably engages a suitable fixed surface, such as theusual anvil "(not shown), so that, what is in effect a depth control, orcontrol of radial movements inwardly and outwardly, of a lens L ingrinding engagement with wheel G is obtained.

The clamping jaw 52 is mounted 'on a suitable idler shaft 52a whichisjournaled in a side wall of the reentrant .portion 80a of coverstructure "80, and which mounts a biasing Spring 5211 by which elarnping'jaw sz is spring loaded to eifect clamping "of a lens blank be;- tweenit and clamping jaw 51. 'An externally threaded rod 520 is threaded intoa bushing in aside wallof cover structure 80 and 'mounts it at its outerend a handszwheel 52d, for effecting adjustment of clamping J r.

Shaft 53 is driven from a "shaft 54 journaled "at the under side ofcover 80 inposition with its axis perpe'n dicular to the axis of shaft53, through a set of bevel gears 55. A countershaft 56 is mounted inhorizontally disposed position on and extending across the upper end offrame structure 70, and it is this shaft 56 that forms the hinge axis onand about which the cover structure 80 with the lens blankclampin'g jaws51- 52, 'isrn'o'unted for swinging to and from operative positions asreferred to hereinabove Shaft '56 is journaled 'in and extending betweenabearing boss or block 73a "horizontally disposed at the upper end ofbracket structure 73, and bearings provided in the opposite sidevertical walls of a gear case 7201 mounted on and extending verticallyupwardly from the upper end 'of pedestal or support structure 72. Abushing or sleeve 56a extends outwardly from the outer side of the gearcase 7221 and forms a trunnion or hinge pin on which the adjacent sidewall of cover structure 80 is rotatably mounted by means of an inwardlyprojecting "sleeve 56b. The cover structure 80 is rotatably mounted onthe opposite end of shaft 56 by a bearing 560 in the vertical side wallof the cover structure, so that the cover structure thus has hingesupport at one side on shaft 56 and-at the opposite side on thebea'ringsleeve5'6a. In order to provide for adjustment laterally ofcover structure 80 to adjust a lens L mounted in clamping jaws 51 and 52to position with the lens engaged in beveling groove 33b or engaged withthe edge grinding surface 3321 of grinding Wheel G, the sleeve 56:: is Hinternally threaded and receives therein the externally threaded innerend of an adjusting shaft 56d which is journal'ed in the adjacent sideWall of cover structure 80 and which mountsat its outer end an adjustinghand wheel 562,

The shaft 54 which drives s'haft'53ofthe rotary wo'rk h ldin me hanism,is driven from c'ountersha'ft "56 through a set of bevel gears 57. Thusas cover 80 is swung from and to operative position, that bevel gear 57on shaft 54 will ride around the bevel gear 57 o'n shaft 56, so thatdriving connection ismaintained at'al'l timesbetween counter-sha'ft'56and the shaft '53 of the wor holdingmechanism.

The countershaft 56 is driven from the "motordrive'n, grinding wheeldriving shaft 10, through a "speed reduc- 'tion gear train R whichincludes, in this exam le a spur gear mounted on a shaft91which isjoinnaled'in and extending across-the lower side'of gear case 7221 inp'o's'ition with its axis parallel with the axis 'ofdrivir'fgshaft 10."A Wormwheel 9-2 is mounted 'onsh'aft 91 and is in driven engagementwitha worm '93e1ra-suart: 94w hifch is journaled in and extendingaerosscol'umn structure 72 intermediate shaft 10' and shaft-91 withitsaxis perpendie ular to the axes of the latter shafts. A worm wheel 95 isfixed on shaft '94 in positionabovedriving shaft 10. A worm96 fixedonshaft 10-is"in driving meshfwith the worm 95 at the underside thereof.Thus, shaft lfidrives gear 90 through worm '96, worm wheel 95, shaft 94,Worm 9.3 "and worm wheel "92. Theeountersh t- "*6 mounts thereona spurgear 97 inmesh-with gear9 *on shaft-91, so thatgear 97 is thereby drivento rotate the eeuntershan sa. Retatien bf shaft efi will thrwgh eliatt54, bevel gears 57 and bevel gears 55, effect rotation of shaft 53 tothereby revolve a lens L mounted in clamping jaws 51 and 52. The gearratios through the above identified'train of gears and shafting is suchthat a lens L mounted in the clamping jaws 51 and 52 will be revolved ata rate of one (1) R. P. M.

The location and positioning of the grinding wheel deflecting pins 40and 41 relative to the grinding wheel G and to a lens L mounted inposition clamped between jaws 51 and 52, and the relative position ofthe lens L to the vertical plane passing through the axis of the wheelG, are shown by Fig. 2 in particular. It will be noted that a line a-bdrawn intersecting the axes of the diametrically opposite pins 40 and 41and passing through the center of the ball member 20 is perpendicular toa line c-d drawn through the axis of lens blank L and the center of ballmember 20. If unrestrained by the pins 49 and 41, the grinding wheel Gwould when rotated by shaft 10 at a sufficient rate of speed besubjected to centrifugal forces developing a gyroscopic action whichwould cause wheel G to assume and maintain a position in a plane ofrotation perpendicular the axis of shaft 10 about the true center of theball member 20. I have established that when displaced laterally to anangle and by forces of a magnitude to balance the wheel restoringforces, that then the grinding wheel assumes when rotated a position ofbalance in which the wheel, in effect, freely floats, so that it may beoscillated in directions axially of shaft 10 by relatively light,laterally acting forces applied thereto. When so oscillated or deflectedwhile maintained in its floating condition of balance the grinding wheelmay be oscillated about the inner ends of pins 40 and 41 as fulcrumpoints and about an axis of oscillation as defined by the line a-b shownin Figs. 2 and 6.

Thus, with a lens L in operative grinding position clamped between jaws51 and 52, and with the head structure 80 lowered to position with lensL having its peripheral edge portion in grinding engagement with thegroove 33b of grinding wheel G under the positive control of the templetT, the wheel G freely floating in its angularly displaced position ofbalance will rock or oscil late freely about axis [1-12 to preciselyfollow the peripheral edge shape or contour laterally of the lens L asthe lens is rotated by the clamping jaws 51 and 52. The lens L thusitself functions as a templet or pattern for effecting and controllingprecisely the oscillations of the freely floating grinding wheel G tocause that wheel to follow the contour laterally of the peripheral edgeportion of the lens blank so as to thereby effectively and efficientlybevel grind the lens.

A machine of my invention for lens edge beveling and embodying thecomponents and the organization and association thereof as hereinbeforedescribed and explained, is also adapted for operation of the grindingwheel G for edge grinding of a lens as distinguished from bevel grindingthereof. The grinding component 33 of the grinding wheel G provides byits peripheral grinding surface 33a which is located between the outeredge thereof and the beveling groove 33b therein, a surface for grindingengagement with a lens to edge grind the same. Such edge grindingoperations are effected without adjustment in or interference with thewheel deflecting pins 40 and 41, or the free floating and oscillation ofgrinding wheel G about the axis ab provided by those pins. In fact, edgegrinding operations are performed by positive oscillation through apredetermined range of the grinding wheel G about the fulcrum providedby the inner ends of pins 46 and 41 and the axis ab, in the same manneras the oscillations effected by thelens during floating of wheel G, butthrough a greater angular range of oscillation.

Referring now to Figs. 1, 2, 5 and 6, I provide a pair of grinding wheeloscillating rods 60 and 61 which are slidably mounted in horizontallydisposed position for reciprocation in and through the bracket structure73, for engaging at their inner ends the outer raceplate 43 of theannular thrust bearing unit 42 mounted on the grinding wheel body 31.The inner ends of rods 60 and 61 engage wheel body 31 at pointsdiametrically opposite and equally spaced from the center of ball member20, at locations 90 around the wheel G from the deflecting pins 40 and41, and in positions with their axes intersected by and perpendicular toa line cd drawn through the axis of rotation of a lens L at the -8center of ball member 20, as will be clear by reference to Figs. 2 and6.

In the example machine, the rods 60 and 61 are arranged for simultaneousaxial movements for reciprocation in opposite directions alternately tothereby oscillate grinding wheel G back and forth about the axis a-bprovided by grinding wheel deflecting pins 40 and 41. The rod 60, inthis example, is displaced inwardly positively under the control of apower driven cam 62 mounted on a shaft 63. The rod 61 is spring loadedby spring unit 610 and functions as a follower or return rod foreffecting oscillation of grinding wheel G in the reverse direction tothat imparted to the wheel on the power stroke of rod 60. Thus, uponcompletion of the power stroke of rod 61 by cam 62, spring loaded rod 61acting on the opposite side of the axis of oscillation, reverses thedirection of oscillation and effects the displacement or deflection ofthe grinding wheel G in the opposite direction. During this returnstroke of rod 61, the low side of cam 62 is opposite the outer end ofrod 60 and the rod is caused to follow around such low side. Uponcompletion of the restoring and reversing stroke of rod 61, the highside of cam 62 will be rotating into engagement with rod 60 so as tothen follow with the power stroke of rod 60.

The cam 62 is fixed on a shaft 63 which shaft is journaled at itsopposite ends in the opposite side walls 64 of a swinging frame 65. Thisframe 65 is pivotally mounted at its upper end along a hinge line spacedabove reciprocating rod 66, so as to position shaft 63 in horizontallydisposed position extending across the outer end of rod 60 with the axisof the shaft 63 perpendicular to the axis of the rod. The pivotal orswinging mounting of frame 65 is effected by pivotally mounting theupper end of the side walls 64 of the frame on a shaft 66 which ismounted and journaled within frame 70 spaced above rod 60 and parallelwith shaft 63. The shaft 66 at its rear end mounts a bevel gear 66athereon which is in driven mesh with a bevel gear 66b fixed on the endof the shaft 91, which shaft is extended from supporting structure 72across and spaced rearwardly from grinding wheel G to position bevelgear 66b for meshing engagement with gear 66a on shaft 66. Thus, shaft66 is continuously driven during operation of the machine from shaft 91which in turn is driven from the driving shaft 10 of the grinding wheel.The swinging frame 65 being rockably hung and depending from shaft 66can thus be rocked between inwardly swung position with cam 62 engagedwith rod 60 and outwardly swung position with the cam in inactive.position disengaged from rod 60. The shaft 63 is driven from shaft 66through the medium of a wide gear 67 fixed on shaft 63 and in constantmesh with a narrow gear 68 fixed on shaft 66. As swinging frame 65 ishung from and rocks on shaft 66 as an axis, it follows thatnotwithstanding the positions to which frame 65 may be swung, the gears67 and 68 remain in constant mesh.

in this example, the swinging frame 65 is constantly biased by a springunit 65s to its inactive position swung outwardly to disengage cam 62from rod 64). In order to swing frame 65 inwardly to operative positionwith cam 62 engaged with the end of rod 60, an operator control isprovided which comprises a horizontally disposed shaft 65a mounted inframe 70 below frame 65, with this shaft extending forwardly to theexterior of the machine where an operating hand lever 65b is mounted onthe shaft end. A depending arm 650 is provided at the outer or undersideof frame 65 and a cam 65d is mounted on shaft 65a with its cammingperiphery engaged against depending arm 65c. Cam 65d presents a highside and a low side and when rotated by shaft 65a to engage the highside with arm 65c, the swinging frame 65 is rocked inwardly against theforces of spring unit 65s, to operative position of the frame with cam62 engaged with rod 60.

The cam 62 is designed to have a throw to oscillate the grinding wheel Gthrough a predetermined range of oscillation for moving grinding surface33a back and forth across the edge of a lens L to effect edge grindingof the lens. However, my invention provides a further feature by whichthe grinding wheel G may be oscillated through a greater predeterminedrange for dressing the grinding surface of the grinding wheel. Incarrying out this feature in the example embodiment, I mount a cam 69 onshaft 63 of swinging frame 65 in position between wages cam 62 and thegear 67 on shaft 63. The swinging frame 65 is thus so hung and mountedon shaft 66 that the frame with its Contained shaft'63 gear 67 and cams62 and 69, can be moved through a limited range axially of shaft 66 ineither direction. Thus, in the illustrated example, when the swingingframe 65 is at its limit of movement rearwardly on shaft 66 as shown inFig. 6, the edge grinding, oscillating cam 62 is in line with rod 60. Bybodily moving swinging frame 65 forwardly on shaft 66 to itslimit offorward movement, the cam 69 is then placed in position for operativeengagement with rod 60, while cam 62 is removed to inactive position.During such movements and in such positions of adjustment, the gears 67and 68 remain in mesh, as the narrower gear 68 merely slides axiallyacross the wide gear 67.

I provide operator controlled means for selectively setting the swingingframe 65 to a position with cam 62 lined up with rod 60 or to' aposition with the cam 69 lined up withthe rod. Such control may take theform ofthe'present example, in which a rod 69a is fixed at its inner endto the forward side wall 64 of swinging frame 65, and extends forwardlytherefrom through the forward or front wall of column structure 76. Asuitable operating knob 69b is fixed on the outer end of rod 69d at theexterior of column structure 70 for ready access by the operator. Toselectively adjust and set the cams 62 and 69 of swinging frame 65, theoperator merely pushes or pulls rod 6%, whichever action required toplace the desired cam in operative relation with push rod 60.

With the example machine, a lens L clamped between jaws 51 and 52, maybe adjusted in an axial direction relative to grinding wheel G by adjustng the cover structure 80 transverse of the machine through the mediumof the hand wheel 566. By such adjustments a lens L can be displacedaxially relative to the bevel grinding groove 33b, in order tocompensate for the various curves encountered with lenses of diiferentprescriptions. Thus, a lens which has a deep curve or one which isnearly flat can be adjusted to a proper position relative to bevelinggroove 33b, so as to fit in the center of the beveling groove andthereby eliminate the uneven lateral pressures that may be caused shouldthe lens be off to one 'side relative to the bevel grinding groove.

In order to perform an edge grinding operation on a lens' L clampedbetween jaws 51 and 52 of the work holding mechanism, the operatorraises cover structure 80 to its inactive position indicated in Figs. 5and 6 by dotted lines, and then actuates the hand lever 65b to rockframe 65 inwardly to place cam 62 in operative association with thegrinding wheel oscillating rod 60. The operator then adjusts the coverstructure 80, if adjustment is required, and lowers the cover structureuntil the lens L is engaged against the grinding wheel G in grindingcontact therewith under the depth or radial movement control of templateT. It is understood, of course, that cams 62 and 69 will have been setby the operator through manual operation of knob 69b, to line cam 62with rod'60. Thereupon, with the machine in operation driven by themotor M, there will result the edge grinding oscillation of wheel Gabout the fulcrum line ab, so that the grinding surface 33aof the wheelis rocked back and forth across and in edge grinding engagement with theperipheral edge of the lens L as the latter is rotated from shaft 53 inthe manner hereinbefore described. The lens L, in the instant example,is rotated at one (1 R. P. M., with the grinding wh'eel G being rotatedat nine hundred (900) R. P. M., while the rods 60 and 61 operate tooscillate wheel G to move the grinding surface 33a thereof at therequired rate hack and forth across the peripheral edge of the lens Lfor the purposes familiar in this artfor lens edge grinding.

When it is desired to convert the machine from edge grinding to lensedge beveling, it is merely necessary for the operator to raise coverstructure 80 to inactive position and then actuate hand lever 65b inadirectio'n to release the swinging frame 65 to the control of springunit 65s, so that frame 65 is swung outwardly to its inactive'positionwith cams 62 and 69 removed from engagernent with rod 66. In suchinactive position of frame 65, the machine may be continued to beoperated from motor M and the cams 62 and 6? will continue to be rotatedeven in the inactive position of the frame due to mend that bevel gears66a and 66b remain in operative mesh. Thus, when frame 65 with its cams62 and 69, is in inactivepos'ition the grinding wheel G'is released toits free floating, balanced position of angular deflection foroscillation'about the fulcrum line a-b under the "controlofa lens Lengaged in' the beveling groove 33b. 2

After rendering the oscillating cams 62 and 69 inactive, the operatormay, after first making any necessary adjustment in the position of lensL by means of hand wheel 56a, lower cover structure 86 to position lensL with its peripheral edge in bevel grinding engagernent in the bevelinggroove 33b of the grinding wheel G, the lens L being of course underthe'control of the template T in the usual manner. Thereafter, as thelens L is revolved in grinding engagement in bevel: ing groove 33b, asgrinding wheel G is rotated, the peripheral contour laterally of lens Lwill effect oscillations laterally in either direction, of the freefloating, balanced grinding wheel G, 'so that the exact contour of thelens peripheral portion is precisely followed by wheel G and a precisionground bevel is formed on and around the lens L.

If it should be desired to dress the grinding surface 33a of grindingwheel G, the cover structure is swung upwardly to its inoperativeposition, as shown in dotted lines Fig. 6. The operator then draws rod69a outwardly by finger knob 69b, to position the Wider throw cam 69 inoperative alignment with the oscillating rod 60. After thus setting cam69,, the operator may then by hand lever 65b rock swinging frame 65inwardly to position the cam 69 in operative engagement with theOSCillating rod 60. With the machine so adjustedthe grinding wheel G isoscillated through a greater degree of oscillation than that utilizedfor edge grinding, so that a dressing tool may be suitably mounted fordressing engagement with grinding surface 33a for dressing that surfaceas the grinding wheel is oscillated under the control of cam 69, rod 60and the spring loaded return rod 61.

It is also evident that various changes, modifications, substitutions,elirninations and additions may be resorted to without departing. fromthe broad spirit and scope of my invention, and hence I do not desire orintend to limit the invention in all respects to the exact and specificexpressions thereof exemplified by the illustrated example machine,except as may be required by specific and intended limitations theretoappearing in any of the appended claims.

What I claim is:

1. In a grinding machine, in combination, a driven shaft; a grindingwheel mounted on said shaft in positive dr ven connection with the shaftfor rotation about the axis of the shaft; said grinding wheel being alsomounted for free and limited oscillation laterally about an axisperpendicular to the axis of said shaft; and deflecting members engagedagainst said Wheel at one side thereof at locations diametricallyopposite the axis of rotation of the wheel adapted to force said wheelto and main: tam it in a predetermined deflected position angularlydisposed relative to a plane perpendicular to the axis of th shafl- 2.In a grinding machine, in combination, a driven shaft, a grinding wheelmounted on said shaft in positive, drlven connection therewith forrotation by the shaft around the shaft axis as a center; said grindingwheel being also mounted on said shaft for free and limited oscillationlaterally in either direction about an axis perpend cular to the axis ofsaid shaft during rotation of said r i eel in mcm a en a one i of sa1dwheel adapted to continuously exert deflecting pressures on said wheelto deflect and maintain said wheel in position on said shaft at an angletoa plane perpendicular to the shaft axis of rotation; and saiddeflecting members prov ding a fulcrum about which said grinding wheelis adapted to be oscillated.

3. In a grinding machine, in combination, a driven shaft; a grindingwheel; means mounting" said grinding wheel on said shaft inpositive'driven connection therewith for rotation of said wheel aboutthe shaftaxis as a center; sa d wheel mounting meansbeing alsoconstructed and arranged for free 'and'limitedoscillation laterally ofsa d wheel on said'shaft abohtan axis perpendicular to the axis of theshaft' during rotation of the wheel by the shaft; means fer ,deflectingsaid 'wheef'late rally 9 nd emaining t e heeiififdeffi jw i si iananposed at an angle to a plane perpendicular to the axis of said shaftduring rotation of the wheel by the shaft, and means adapted to beoperatively engaged with said wheel for positively oscillating saidwheel.

4. In the combination as defined in claim 3, manually controllable meansfor selective operation to engage said oscillating means with ordisengage said oscillating means from said grinding wheel.

5. In a grinding machine in combination, a driven shaft; a grindingwheel mounted on said shaft in positive driven connection therewith forrotation by the shaft around the shaft axis; said grinding wheel beingalso mounted on said shaft for free and limited oscillation laterallyabout an axis perpendicular to the axis of said shaft during rotation ofsaid grinding wheel; a fixed support structure at one side of saidgrinding wheel; and spring loaded pin members slidably mounted in saidsupport structure in positions continuously engaged at diametricallyopposite locations against one side of said grinding wheel tocontinuously exert forces acting on said wheel to maintain said wheeldeflected laterally to a position at an angle to a plane perpendicularto the axis of said shaft at which the centrifugal forces generated byrotation of said wheel tending to restore the wheel to a position in aplane perpendicular to the shaft axis are balanced by the deflectingforces applied to the wheel by said spring loaded pin members.

6. In the combination as defined in claim 5, antifriction bearing meansinterposed between said wheel and the wheel engaging ends of said pinmembers for rotative engagement of said wheel with the adjacent ends ofsaid pin members.

7. In a grinding machine, in combination, a rotary, driven shaft; agrinding wheel mounted on said shaft in positive driven connectiontherewith for rotation about the axis of the shaft; said grinding wheelbeing also mounted for free, limited oscillation laterally about an axisperpendicular to the axis of said shaft; wheel deflecting membersengaged at their inner ends against the adjacent side of said wheel andbeing adapted to continuously exert forces on the wheel acting in adirection to deflect the wheel laterally to a position at which theforces acting on said wheel are balanced with the wheel floating forfree oscillation; said wheel deflecting members constituting fulcrummembers about which said wheel may be freely oscillated; wheeloscillating members engaged with said wheel at diametrically oppositepoints thereon spaced angularly therearound from said wheel deflectingmembers; and means adapted to be engaged with said wheel oscillatingmembers for effecting positive oscillation of said wheel.

8. In combination; a circular grinding wheel providing a peripheralgrinding surface therearound; said grinding surface being formed with abeveling groove therein and therearound concentric with the axis ofrotation of said wheel; said wheel being mounted for oscillationlaterally about an axis perpendicular to the axis of said wheel; meansfor rotating said wheel; means for forcing and maintaining said wheeldeflected laterally to a position at which the forces acting to restoresaid wheel to position in a plane perpendicular to the axis of rotationare balanced by the deflecting forces to cause the wheel to float in acondition of balance for free lateral oscillation; and means formounting a circular work piece in position with its peripheral edgeportion received in grinding engagement in said beveling groove of thegrinding surface of said wheel.

9. In combination, a circular grinding wheel providing a peripheralgrinding surface therearound; said grinding surface being formed with abeveling groove therein and therearound concentric with the axis ofrotation of said wheel; said wheel being mounted for free oscillationthereof laterally about an axis perpendicular to the axis of rotation ofthe wheel; means for rotating said wheel; and means for forcing andmaintaining said wheel deflected laterally to a position at which theforces acting to restore said wheel to position in a plane perpendicularto the axis of rotation are balanced by the deflecting forces to causethe wheel to float in a condition of balance for free oscillation by theapplication thereto of relatively light, laterally acting forces.

10. In combination, a circular grinding wheel providing a peripheralgrinding surface therearound; means for rotating said wheel; saidgrinding surface'being formed with a beveling groove therein andtherearound concentrio with the wheel axis of rotation; said grindingwheel being mounted for free oscillation thereof about an axisperpendicular to the axis of rotation of the wheel; rotatable workholding means adapted to mount therein a circular work piece forrotation thereby about an axis generally parallel with the axis ofrotation of said grinding wheel; said work holding means being mountedfor movement to and from an operative position with the peripheral edgeof a work piece mounted therein held in bevel grinding engagement insaid beveling groove of the grinding wheel; deflecting means mountedindependently of said work holding means for forcing and maintainingsaid grinding wheel deflected laterally to a position at which theforces acting thereon to restore said wheel to a position in a planeperpendicular to the axis of rotation are balanced by the deflectingforces to cause the wheel to float in a condition of balance for freelateral oscillation under the action of forces applied thereto laterallyby the contour of the peripheral edge portion of a work piece when ingrinding position in said beveling groove.

11. In a grinding machine, in combination, a driving shaft; a grindingwheel mounted on said shaft in driven connection therewith; said wheelbeing also mounted on said shaft for oscillation laterally relative tosaid shaft on and about an axis perpendicular to the axis of said shaft;a work holder for supporting a work piece in grinding engagement withsaid grinding wheel; and means independent of said work holder forforcing and maintaining said wheel deflected laterally to a position atan angle to a plane perpendicular to the axis of said shaft at which thecentrifugal forces generated by rotation of said wheel are balanced bythe opposing deflecting forces exerted by said means.

12. In a grinding machine, in combination; a driven shaft; a sphericalmember fixed on said shaft concentric therewith for rotation with theshaft; a grinding wheel mounted on said spherical member for oscillationlaterally on and about an axis perpendicular to said shaft; meansproviding a positive driven connection between said spherical member andsaid wheel for efiecting rotation of said wheel with said sphericalmember and shaft about the axis of said shaft as a center; a work holderfor supporting a work piece in grinding engagement with said grindingwheel; and means independent of said work holder and of a work piecemounted therein for positively oscillating said wheel on and reltaive tosaid spherical member and shaft through a predetermined range ofoscillation.

13. In a grinding machine, in combination, a driven shaft; a sphericalmember mounted on said shaft in fixed driven connection therewith; agrinding wheel mounted on said spherical member for oscillationlaterally thereon about an axis perpendicular to the axis of said shaft;means connecting said grinding wheel in positive driven connection withsaid spherical member and adapted to constrain said grinding wheelagainst rotation about the axis of said shaft; a work holder forsupporting therein a work piece in grinding engagement with saidgrinding wheel, means independent of said work holder and of a workpiece supported therein for constraining said grinding wheel to apredetermined position of angular deflection relative to a planeperpendicular to the. axis of ro tation of said shaft; and saidconstraining means pro- 1 viding a fulcrum for oscillation of saidgrinding wheel thereon as an axis.

14. In a grinding machine, in combination, a rotary driven shaft; agrinding wheel mounted on said shaft in dr ven connection therewith;said grinding wheel being also mounted on said shaft for free andlimited oscillation laterally on and about an axis perpendicular to saidshaft while said grinding wheel is being rotated by said shaft; a workholder for supporting therein a work piece in grinding engagement withsaid grinding wheel; and mechanism independent of said work holder andof a work piece supported therein for forcing said grinding wheellaterally to and maintaining the said grinding wheel in a predetermineddeflected position at an angle to a plane perpedicular to the axis ofsaid shaft.

15. In a grinding machine, in combination, a driven shaft; a grindingwheel mounted on said shaft in positive driven connection therewith forrotation by said shaft about the shaft axis as a center; said grindingwheel being also mounted on said shaft for free and limited oscillationlaterally on and about an axis .perpendicular to the arms of said shaft;a work holder for supporting a work piece therein in grinding engagementwith said grinding wheel; and deflecting members engaging with saidgrniding wheel and being adapted to force said grinding wheel to andmaintain it in a deflected position on said shaft at a predeterminedangle to a plane perpendicular to the axis of rotation of said wheelduring rotation of the wheel by said shaft.

16. In an optical lens grinding machine, in combination; a framestructure; a rotary driven shaft mounted on said frame structure; acircular grinding wheel mounted on said shaft for rotation therewith;said grinding wheel being also mounted on said shaft for deflectionlaterally thereon about an axis perpendicular to the axis of rotation ofsaid shaft; said grinding wheel having a peripheral grinding surfacetherearound formed with a lens edge beveling groove therein andtherearound concentric with the axis of rotation of said grinding wheel;the portion of said grinding surface between said groove therein and anadject side of said wheel being formed to provide a lens edge grindingsurface; rotatable work holding means mounted on said frame structureadapted to mount therein a lens blank for rotation thereby about an axisgenerally parallel with the axis of rotation of said grinding wheel;said work holding means being mounted and supported from said framestructure for movements to and from an operative position with theperipheral edge portion of a lens blank mounted therein held in grindingengagement with either said beveling groove or said edge grindingportion of said grinding surface of said grinding wheel; grinding wheeldeflecting means supported from said frame structure for forcing andmaintaining said grinding wheel deflected laterally to a position atwhich the forces acting thereon to restore said wheel to position in aplane perpendicular to the axis of rotation of said wheel are balancedby the deflecting forces applied thereto to cause said grinding wheel tofloat in a condition of balance for free oscillation laterally thereofindependently of said shaft; and mechanism supported from said framestructure for effecting positive oscillation of said grinding wheel.

17. In the combination as defined in claim 16, said grinding wheeloscillating mechanism being mounted for movements to and from positionin operative oscillating association with said grinding wheel; and meansfor selectively moving said oscillating means to or from operativeassociation with said grinding wheel.

18. In the combination as defined in claim 16, said grinding wheeloscillating mechanism including a push rod mounted and supported fromsaid frame structure for reciprocation axially with one end thereofbeing engaged against the adjacent side of said grinding wheel; and adriven cam in operative engagement with said push rod for reciprocatingsaid rod.

19. In the combination as defined in claim 16, said grinding wheeloscillating mechanism including a push rod supported from said framestructure and being mounted for axial reciprocation with one end thereofengaged against the adjacent side of said grinding wheel at a locationoffset from the axis of rotation of said grinding wheel; a spring loadedpush rod supported from said frame structure and being mounted for axialreciprocation with one end thereof engaged at the adjacent side of saidgrinding wheel at a location thereon diametrically opposite said firstmentioned push rod; and a driven cam supported from said frame structurein position engaged with said first mentioned push rod for reciprocatingsaid rod to effect oscillation of said grinding wheel.

20. In the combination as defined in claim 16; said grinding wheeloscillating mechanism being comprised of parallel push rods reciprocallymounted in positions with the inner ends thereof engaged with theadjacent side of said grinding wheel at diametrically opposite locationsthereon; mechanism for reciprocating said push rods to oscillate saidwheel on and relative to said shaft; and said push rod reciprocatingmechanism being mounted on said frame structure for movements to andfrom position in operative association with said push rods.

21. In the combination as defined in claim 16; said grinding wheeloscillating mechanism being selectively adjustable to cause saidmechanism to oscillate said grinding wheel through differentpredetermined degrees of oscillation, respectively.

22. In the combination as defined in claim 16; said work holding meansbeing adjustable for selectively positioning a lens blank mountedtherein axially relative to said bevel groove for grinding engagement insaid groove; and operator controlled means for selectively adjustingsaid work holding means.

23. In a grinding machine, in combination; a frame structure; a rotarydriven shaft mounted on said frame structure; a grinding wheel mountedon said shaft in positive driven connection therewith for rotation aboutthe axis of said shaft; said grinding wheel being also mounted on saidshaft for free and limited oscillation laterally about an axisperpendicular to the axis of said shaft; a set of push rods mounted onsaid frame structure for reciprocation in positions with the inner endsthereof engaged against the adjacent side of said grinding wheel atdiametrically opposite locations thereon; a support structure pivotallymounted and supported from said frame structure; a driven cam rotatablymounted on said support structure and being movable therewith as a unit;said support structure and cam being mounted relative to said push rodswhereby in one position of said support structure said cam is inoperative engagement with one of said push rods and in another positionof said support structure said cam is disengaged from such push rod; andoperator controlled means mounted and supported from said framestructure for moving said support structure and cam as a unit tooperative position with said cam engaged with such push rod.

24. In the combination as defined in claim 23, the push rod of said setof push rods that is not engageable with said cam being spring loadedfor biasing said wheel and cam engaged push rod through a return stroke.

25. In a grinding machine, in combination, a frame structure; a rotarydriven shaft on said frame structure; a grinding wheel mounted on saidshaft in driven connection therewith for rotation thereby; said grindingwheel being also mounted on said shaft for limited oscillation laterallyindependently of said shaft about an axis perpendicular to the axis ofthe shaft; mechanism supported from said frame structure and including areciprocal member for oscillating said grinding wheel on and relative tosaid shaft; a support structure mounted on said frame structure forswinging toward and from an operative position relative to saidreciprocal member; cams rotatably mounted on said support structure forselective engagement, respectively, with said reciprocal member whensaid support structure is in operative position relative thereto; eachof said cams being formed to actuate said reciprocal member through astroke of different length; operator controlled means for selectivelypositioning any one of said cams on said support structure for operativeengagement with said reciprocal members; and an independent operatorcontrolled means supported from said frame structure for swinging saidsupport structure to and from an operative position engaging a cam withsaid reciprocal member.

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